Organization of the murine immunoglobulin VH complex in the inbred strains.

Deletion mapping analyses have been employed to order the heavy chain variable region (VH) gene families in three inbred murine strains. These nine VH gene families have been positioned with respect to the J558 and 3660 VH families in A/J (Ighe) as follows: 3609-J558-(J606,VGAM3-8,S107)-3660-(X24,Q52,7183 )-DH. Maps generated with respect to J558 in the BALB/c (Igha) and C57BL/6 (Ighb) strains are consistent with these results. The organization of the VH complex produced by deletion mapping is quite different from the accepted map generated by other methods, particularly in that J558 is more DH distal and 3660 is more DH proximal than previously thought. The order presented here is compatible with VH rearrangement frequencies suggesting preferential utilization of DH-proximal VH gene segments. Our data also indicate that interspersion of some VH family members may be a common feature of the murine VH complex since the 3609 VH family is interdigitated in the three strains and a Q52 VH gene segment is interspersed in C57BL/6.     

One heavy chain variable region gene segment subfamily in the BALB/c mouse contains 500-1000 or more members

Nucleic acid hybridization studies suggest that 500-1000 or more heavy chain variable (VH) gene segments related to one VH gene segment (J558) are present in the genome of the BALB/c mouse. The implications of this result regarding the overall size, sequence organization, and evolution of the mouse family of VH gene segments are discussed.     

Complete heavy and light chain variable region sequence of anti-arsonate monoclonal antibodies from BALB/c and A/J mice sharing the 36-60 idiotype are highly homologous

Structural and serologic studies on murine A/J monoclonal anti-arsonate antibodies resulted in the identification of a second idiotype family (Id36-60) in addition to the predominant idiotype family (IdCR). Id36-60, unlike IdCR, is a dominant idiotype in the BALB/c strain but is a "minor" idiotype in the A/J strain. The complete heavy and light chain variable region (VH and VL) amino acid sequences of a representative Id36-60 hybridoma protein from both the A/J and BALB/c strains have been determined. There are only four amino acid sequence differences between the VH of antibody 36-60 (A/J) and antibody 1210.7 (BALB/c). Two of these differences arise from single nucleotide changes in which the A/J and BALB/c Id36-60 VH germline gene sequences differ. The two other differences are the result of somatic mutation in hybridoma protein 36-60. In addition, Id36-60 heavy chains employ the same D and JH3 segments in both strains. The entire Vk2 VL of 36-60 and 1210.7 differ by only two amino acids, suggesting that like the heavy chains, they are derived from highly homologous VL genes. The same Jk segment is used in both antibodies. A comparison of the amino acid sequence data from Id36-60-bearing hybridomas suggests that a heavy chain amino acid difference accounts for the diminished arsonate binding by the 1210.7 hybridoma protein. Because the 1210.7 heavy chain is the unmutated product of the BALB/c VH gene, somatic mutation in VH may be required to enhance Ars affinity in this system.     

Complete amino acid sequences of the heavy and light chain variable regions from two A/J mouse antigen nonbinding monoclonal antibodies bearing the predominant p-azophenyl arsonate idiotype

The immune response to p-azophenyl arsonate (Ars) in A/J mice is dominated by a cross-reactive idiotype (CRI or IdCR). IdCR+ hybridoma proteins 1F6 and 3D10 produced in a single mouse by immunization with a monoclonal anti-IdCR antibody did not bind Ars [Wysocki, L., & Sato, V. (1981) Eur. J. Immunol. 11, 832-839]. The preservation of idiotype coupled with lack of antigen binding in the same molecules provoked an examination of their primary structures in order to localize sites involved in binding to antigen and to anti-idiotypes. The VH sequence of antibody 3D10 was determined by Edman degradation of intact chains and fragments generated by CNBr, hydroxylamine, and o-iodosobenzoic acid cleavage, by trypsin and V8 protease digestion, and by sequence analysis of mRNA. The 1F6 VH sequence was reported previously [Smith, J. A., & Margolies, M. N. (1984) Biochemistry 23, 4726-4732]. The VL sequences of 1F6 and 3D10 were determined by Edman degradation of intact chains and peptides generated by cleavage with o-iodosobenzoic acid and digestion with trypsin and chymotrypsin. Both 1F6 and 3D10 are encoded by the same VH, VK, D, and JK gene segments as are IdCR+ Ars-binding antibodies. However, 1F6 and 3D10 employ the JH4 gene segment rather than JH2. Antibodies 1F6 and 3D10 share several somatic mutations, suggesting a common clonal origin, but manifest individual mutations as well. By comparison with Ars-binding IdCR+ molecules, the substitutions in 1F6 and 3D10 likely responsible for the lack of Ars binding are localized to the heavy chain D-JH junction and/or to a substitution in light chain CDR 3.     

Variable region sequence analysis of anti-DNA antibodies: evidence for a family of closely related germ-line VH genes encoding lupus autoantibodies.

Cloning and sequencing of the V regions of the anti-DNA monoclonal antibodies (mAbs), H438 and H130, indicate that H438 is encoded by a J558 VH gene, a single D region nucleotide, and unmutated JH1, V kappa-1C and J kappa 1 genes, and the H130 L chain is encoded by a V kappa-21 subgroup gene J kappa 1 gene. Identification of VH438, which shared VH hybridization pattern with 6% of a panel of 352 MRL/lpr hybridomas, suggests that the frequency of J558 use among spontaneously activated B cells in MRL/lpr mice is greater than previously reported. The VHH438 J558 family gene is identical to VHPAR, which encodes the independently derived MRL/lpr autoantibody, MRP-2, and is highly homologous to the previously reported VHH130, which is identical to a BALB/c germ-line VH gene. Comparison of consensus sequences of homologous autoantibodies and previously reported restriction mapping suggest that a minimum of three highly related J558 germ-line genes encode lupus autoantibodies.     

A rabbit antiserum detects a VH J558 subgroup marker highly expressed among anti-alprenolol antibodies

A rabbit antiserum raised against anti-alprenolol mAb 14C3 detects common antigenic determinants (ADC3) in 10 out of 14 anti-alprenolol mAb that use different germ-line VH and/or Vk genes. The anti-14C3 antiserum binds only to H chains in immunoblots, therefore suggesting that at least part of the ADC3 determinants may be encoded by H chain V region genes. Analysis of VH gene family usage among the anti-alprenolol mAb reveals that the expression of ADC3 correlates with utilization of VH genes that belong to the J558 gene family, regardless of the JH, Vk, and Jk genes. To determine whether the ADC3 determinants are general V region markers or whether they are unique to anti-alprenolol antibodies, we have extended our analysis to a random panel of antibodies that also use VH genes of the J558 family. Among 23 mAb of various specificities, 14 react with the anti-14C3 antiserum in immunoblot and in ELISA, irrespective of antibody specificity. Adsorption of the antiserum on one of these positive antibodies results in a loss of reactivity toward both anti-alprenolol and unrelated antibodies. Therefore, several but not all antibodies that use a J558 VH gene also express the complete set of epitopes defining ADC3. These results strongly suggest that ADC3 are markers of a subset of J558 VH gene products. The anti-14C3 antiserum may thus constitute a "serologic probe" for identification of a VH gene subgroup from the J558 gene family.     

Molecular analysis of immunoglobulin heavy chain genes coding for idiotypic and anti-idiotypic antibodies involved in B-B cellular interaction.

We recently reported that a unique B cell clone (B19-1d), specific for a cross-reactive idiotype (CRI) on MOPC104E myeloma protein (M104E), enhances Igh-restricted CRI+ antibody production. In this paper, we report the nucleotide sequences of immunoglobulin heavy chain variable regions (VH) of both M104E and B19-1d-derived hybridoma (HB19) antibodies. The sequence data revealed that both belong to the J558 germ line VH gene subfamily. Strikingly, not only the VH region, but also the leader sequences of M104E and HB19 are very similar to each other at 88% (VH) and 91% (leader) homology, but they use different D and J segments. The VH region sequence similarity is highest among the germ line VH gene sequences of the BALB/c J558 subfamily so far screened. Southern hybridization data, using 5'-noncoding regions of either M104E or HB19 genomic VH gene clones as probes, revealed that both VH genes are conserved in the M104E CRI producer strains of mice. Moreover, these probes show the restriction length polymorphism pattern of mouse VH genes in various strains. That the HB19 VH gene locates to the 5' upper arm of the M104E VH gene on the chromosome was suggested by Southern blot hybridization. Immunoglobulin VH gene restriction of idiotypic and antiidiotypic B-B cellular interaction is discussed from a molecular point of view.     

Structure, map position, and evolution of two newly diverged mouse Ig VH gene families.

We have characterized two novel mouse VH gene families, VH3609N and VHSM7. These VH families have recently diverged from previously defined VH families. The VH3609N family, which may contain only one member in most inbred strains of mice, shares sequence similarity with the VHJ606 family and is located to the 3' side of VHJ606. VHSM7, with at least three members, is related to the VHJ558 family but maps 3' of VHJ558. These findings suggest that physical displacement of VH sequences may facilitate their subsequent divergence. During the early stages of VH gene family evolution that are exemplified by these new families, amino acid replacements have been selected against in frame-work regions and selected for in complementarity-determining regions. This pattern of nucleotide substitution appears to reflect evolutionary pressures to maintain germ-line VH diversity and, possibly, to select for new antibody specificities, as well as to select against mutations resulting in aberrant Ig. The classification of VH sequences with borderline similarity to previously defined VH families is discussed.     

Characteristics of two idiotypic subfamilies of murine anti-p-azobenzenearsonate antibodies

A family of antibodies bearing a common or cross-reactive idiotype, termed CRIC, predominates in the response of most BALB/c mice to the p-azobenzenearsonate (Ar) hapten, but represents a minor component of the anti-Ar response of most A/J mice. Previous results have suggested that the VH region of CRIC is encoded by two different germ-line genes in both strains. We have determined extensive mRNA sequences for VH and VL, developed specific idiotypic reagents and measured affinities for two subfamilies of CRIC, designated CRIC1 and CRIC2. Both were found to be minor components of A/J anti-Ar antibodies, and CRIC1, but not CRIC2, is a major component of the BALB/c response. The two subfamilies utilize different VH germ-line genes but the same, or nearly identical V kappa genes. The VH nucleotide sequences of CRIC1 and CRIC2 exhibit approximately 90% homology. The D regions of both families are short (one or two amino acid residues) and some can be accounted for on the basis of known JH sequences alone. Affinity differences may account for the dominance of CRIA over CRIC1 and CRIC2 in A/J mice, but results obtained with allotype-congenic mice indicate that background (non-V region) genes are also important in controlling levels of expression of the CRIC1 idiotype. Our data suggest that the A/J germline VH gene that gives rise to the CRIC2 family of antibodies may be identical with a previously sequenced BALB/c germ-line VH gene. On the basis of these and earlier data it is suggested that extensive differences between inbred strains of mice in their complements of VH genes do not result from the accumulation of many mutations in these genes. An alternative possibility is that the differences arise from deletions and/or duplications of VH genes.     

Characteristics of murine monoclonal anti-CD4. Epitope recognition, idiotype expression, and variable region gene sequence.

We have characterized a series of mouse monoclonal anti-CD4 and describe both their CD4 epitope recognition and Id expression. We also determined the V region gene sequences of these antibodies in an attempt to correlate epitope recognition and Id expression with V region sequence. All of these preparations recognize epitopes that cluster around the HIV gp120 binding site on the human CD4 molecule. However, we observed differences in epitope recognition among the anti-CD4 preparations, based on either competitive inhibition assays or functional assays, such as syncytium inhibition. Analysis of Id specificities using a polyclonal anti-Id generated against anti-Leu 3a indicated that five of the seven monoclonal anti-CD4 expressed a shared Id. Based on V region gene sequences, the V region kappa-chain (V[kappa]) from each of the seven antibodies was encoded by the V[kappa]21 gene family and expressed the J[kappa]4 gene segment. Those preparations that expressed the shared Id with anti-Leu 3a have virtually identical V[kappa] sequences, with a high degree of homology in the CDR. The VH region gene sequences of six of the seven antibodies also shared overall homology and appeared to be encoded by the J558 VH gene family. The seventh anti-CD4 VH region is encoded for by the VHGAM gene family. The majority of these antibodies used JH3 gene segment, although the JH2 and JH4 gene segments were also represented. In addition, several of these antibodies share a common sequence organization within their V-D-J joining regions that appears to involve N and P sequences to generate unique D segments. Together, these data suggest that differences in epitope recognition among the monoclonal anti-CD4 may reflect sequence variability primarily within the CDR3 region of both V[kappa] and VH. The basis for the detection of a shared Id most likely reflects the high degree of homology within the V[kappa] region sequences. In addition, these data, which are based on a limited analysis, suggest the possible restricted use of V region germ-line gene families in the secondary antibody response of BALB/c mice to specific epitopes on the human CD4 molecule.     

An immunoglobulin heavy chain variable region gene is generated from three segments of DNA: VH, D and JH

We have determined the sequences of separate germline genetic elements which encode two parts of a mouse immunglobulin heavy chain variable region. These elements, termed gene segments, are heavy chain counterparts of the variable (V) and joining (J) gene segments of immunoglobulin light chains. The VH gene segment encodes amino acids 1-101 and the JH gene segment encodes amino acids 107-123 of the S107 phosphorylcholine-binding VH region. This JH gene segment and two other JH gene segments are located 5' to the mu constant region gene (Cmu) in germline DNA. We have also determined the sequence of a rearranged VH gene encoding a complete VH region, M603, which is closely related to S107. In addition, we have partially determined the VH coding sequences of the S107 and M167 heavy chain mRNAs. By comparing these sequences to the germline gene segments, we conclude that the germline VH and JH gene segments do not contain at least 13 nucleotides which are present in the rearranged VH genes. In S107, these nucleotides encode amino acids 102-106, which form part of the third hypervariable region and consequently influence the antigen-binding specificity of the immunoglobulin molecule. This portion of the variable region may be encoded by a separate germline gene segment which can be joined to the VH and JH gene segments. We term this postulated genetic element the D gene segment, referring to its role in the generation of heavy chain diversity. Essentially the same noncoding sequences are found 3' to the VH gene segment and as inverse complements 5' to two JH gene segments. These are the same conserved nucleotides previously found adjacent to light chain V and J gene segments. Each conserved sequence consists of blocks of seven and ten conserved nucleotides which are separated by a spacer of either 11 or 22 nonconserved nucleotides. The highly conserved spacing, corresponding to one or two turns of the DNA helix, maintains precise spatial orientations between blocks of conserved nucleotides. Gene segments which can join to one another (VK and JK, for example) always have spacers of different lengths. Based on these observations, we propose a model for variable region gene rearrangement mediated by proteins which recognize the same conserved sequences adjacent to both light and heavy chain immunoglobulin gene segments.     

Sequences of the VH and VL regions of murine monoclonal antibodies against 3-fucosyllactosamine

Many mAb that bind the carbohydrate antigenic determinant 3-fucosyl-lactosamine (3-FL), Gal beta 1-4[Fuc alpha-3]GlcNAc-R have been raised in BALB/c mice, and we are studying the structure and regulation of these antibodies. In this report, we present the first information about their amino acid sequences and the Ig gene segments used to encode them. V regions of the H and L chains of three anti-3-FL antibodies, PMN6, PMN29, and PM81, were sequenced by a combination of mRNA and amino acid sequencing. The L chain sequences of PMN6 and PM81 antibodies indicate that their VK and JK regions are encoded by VK24B and JK1 germ-line genes, respectively. The nucleotide and amino acid sequences of the H chains suggest that the three anti-3-FL antibodies are encoded by the VH441 gene segment of the X24 VH family, and this conclusion was supported by Southern filter hybridization with VH441 and JH3-JH4 probes. PMN29 has at least 11 amino acid substitutions, which is an unusually large amount of somatic mutation for an IgM antibody. Previous analyses of BALB/c genomic libraries with VHX24 and VH441 probes make it unlikely that this VH family contains additional germ-line genes, but this possibility cannot be excluded. All three antibodies use the DQ52 and JH4 gene segments. The single VH and VL gene segments used to encode the anti-3-FL antibodies is in contrast to the multiple VH and VL segments used by antibodies against other carbohydrate Ag such as alpha 1-6 dextran and group A streptococcal carbohydrate. VH441 also encodes the VH regions of antibodies against galactan and levan (beta 2-6 fructosan). The similarities among VH segments of antibodies against 3-FL, levan, and galactan, and the striking differences in their CDR3 sequences, suggest that CDR3 plays an important role in the formation of the Ag binding site. The use of a single VH segment from the smallest VH gene family by antibodies against at least three different carbohydrate determinants is noteworthy. It raises the possibility that the amino acid sequence encoded by VH441 has some general structural features that make it particularly well adapted for binding to carbohydrate sequences.     

Relationship of human variable region heavy chain germ-line genes to genes encoding anti-DNA autoantibodies

In order to identify the V region genes encoding systemic lupus erythematosus (SLE)-derived anti-DNA autoantibodies, we have determined the nucleotide sequence of heavy chain mRNA from several DNA-binding immunoglobulins secreted by human hybridomas. We used the technique of cDNA primer extension for determining sequences of the VH, D, and JH gene segments of anti-DNA autoantibodies from three different primary hybridoma growths from an SLE patient and one hybridoma from a leprosy patient. Immunoglobulins from two of the SLE hybridomas expressed the same idiotype, Id-16/6, which is also expressed on immunoglobulins in sera of patients with active SLE. Their mRNA sequences showed complete homology to each other in the V, D, and J genes and more than 99% homology to the VH26 germ-line gene sequence, a member of the human VHIII gene family. The VH mRNA sequence of the third SLE hybridoma, 21/28, which was idiotypically unrelated to the other two, was 93% homologous to a different VH germ-line gene sequence, HA2, a member of the human VHI gene family. The fourth anti-DNA-producing hybridoma, 8E10, was derived from a leprosy patient of different ethnic origin than the SLE patient. It was idiotypically related to 21/28 and expressed a VH segment gene identical to that of 21/28. Hybridomas 21/28 and 8E10 shared sequence homology with the VH26 anti-DNA antibodies in the first complementarity-determining region. In addition, 21/28 shared sequence homology with the Id-16/6+ group in the region encoded by the D and J gene segments. Our findings indicate that some SLE autoantibodies are encoded by unmodified or scarcely modified VH germ-line genes that are conserved in the human population and identify two distinct VH germ-line genes that can encode segments of anti-DNA immunoglobulins.     

Diverse organization of immunoglobulin VH gene loci in a primitive vertebrate.

The immunoglobulin (Ig) heavy chain variable (VH) gene family of Heterodontus francisci (horned shark), a phylogenetically distant vertebrate, is unique in that VH, diversity (DH), joining (JH) and constant region (CH) gene segments are linked closely, in multiple individual clusters. The V regions of 12 genomic (liver and gonad) DNA clones have been sequenced completely and three organization patterns are evident: (i) VH-D1-D2-JH-CH with unique 12/22 and 12/12 spacers in the respective D recombination signal sequences (RSSs); VH and JH segments have 23 nucleotide (nt) spacers, (ii) VHDH-JH-CH, an unusual germline configuration with joined VH and DH segments and (iii) VHDHJH-CH, with all segmental elements being joined. The latter two configurations do not appear to be pseudogenes. Another VH-D1-D2-JH-CH gene possesses a D1 segment that is flanked by RSSs with 12 nt spacers and a D2 segment with 22/12 spacers. Based on the comparison of spleen, VH+ cDNA sequences to a germline consensus, it is evident that both DH segments as well as junctional and N-type diversity account for Ig variability. In this early vertebrate, the Ig genes share unique properties with higher vertebrate T-cell receptor as well as with Ig and may reflect the structure of a common ancestral antigen binding receptor gene.     

VH gene analysis of spontaneously activated B cells in adult MRL-lpr/lpr mice. J558 bias is not limited to classic lupus autoantibodies

To determine the genetic origins of lupus auto-antibodies, we analyzed the relationship between VH gene usage and auto-Ag-binding properties of 352 B cell hybridomas derived from MRL-lpr/lpr mice. The hybridomas were derived from neonatal, 1-month-old, 3-month-old, and 6-month-old mice. The experimental strategy provided that the hybridomas were monoclonal at initial evaluation, so the Ag binding and V gene frequencies of the entire population could be determined. Initially, 1032 Ig-producing hybridomas were evaluated for binding to six Ag; VH gene family use was determined in 119 anti-DNA and anti-rabbit thymus extract (RTE) antibodies (autoantibodies) and in 233 age-matched Ig that did not bind to any of the six Ag (nonbinders). Neonatal B cells, including cross-reactive IgM autoantibodies and nonbinder IgM, used relatively 3' VH genes. The majority of B cells in adult mice used VH genes of the J558 family. Although J558 use was significantly higher among the autoantibodies (anti-DNA and anti-RTE) than among the nonbinder Ig, this difference was due to a higher frequency of J558 use by 1-month-old mice. At 3 months, J558 use by the nonbinder Ig increased to the same frequency of J558 use as in the autoantibody population. J558 use in both groups of antibodies exceeded a previously reported estimation of J558 expression in the functional B cell repertoire of young adult MRL-lpr/lpr mice. Several subgroups of antibodies that share properties with pathogenic Ig, including IgG, cross-reactive Ig, and anti-dsDNA autoantibodies, demonstrated a marked preferential expression of the J558 family. These results suggest that there is an age-related bias in the activation of B cells using J558 VH genes in MRL-lpr/lpr mice that is under the influence of a selective force distinct from, or in addition to, an ssDNA or RTE auto-Ag-driven response.     

The generation of major and minor idiotype-bearing families of anti-p-azophenylarsonate antibodies; stochastic utilization of VH gene segments

An average of 50% of anti-p-azophenylarsonate (Ars) antibodies bear a cross-reactive idiotype, IdCR, and an average of 15% bear a relatively minor idiotype, Id, in A/J mice. To begin to investigate the processes that influence the expressed levels of these idiotype-bearing antibodies in serum, we have examined the frequency among preimmune B cells of cells that utilize the heavy chain variable region gene segment (VH) needed for IdCR and that which is needed for Id anti-Ars antibody expression. Our results indicate these VH gene segments are functionally rearranged at frequencies one would expect for random usage. The frequency of VH gene segment utilization is similar to, if not higher than, that of VHCR, arguing that the predominance of IdCR-over Id-bearing antibodies is not due to preferential usage of the VHCR gene segment. In addition to the analysis of Ars-immune sera pooled from several mice, we have examined 20 individual A/J mice to determine whether the relative serum levels of IdCR- and Id-bearing antibodies are strictly regulated relative to each other. Among individuals, we find that IdCR and Id antibody levels fluctuate over a 28-fold and a 120-fold range, respectively. The ratio of IdCR to Id antibody levels was found not to be strictly regulated, varying over a 300-fold range. Linear regression analysis of IdCR relative to Id concentrations shows a correlation coefficient of only 0.093. Indeed, rare mice can be found that generate greater levels of Id-bearing antibodies than those bearing IdCR. These results are indicative of a stochastic process involved during the generation of these IdCR-and Id-bearing antibody families. Models accounting for the generation of this highly variable serologic response derived from a preimmune repertoire in which VH gene segments are equivalently utilized are discussed.     

Autoantibodies to thyroglobulin are encoded by diverse V-gene segments and recognize restricted epitopes.

Murine experimental autoimmune thyroiditis has been used as a model for human autoimmune thyroiditis. Experimental autoimmune thyroiditis is induced in mice by immunization with mouse thyroglobulin (Tg) in CFA. To characterize the antibodies to this autoantigen, we have studied the binding specificities and determined the nucleotide sequences of monoclonal anti-Tg antibodies. The specificities of the mAb for determinants on Tg varied extensively. Seven of 16 mAb showed reactivity to only mTg, 4 reacted to Tg from more than one species and four reacted to a variety of Ag. Many of the mAb were competitively inhibited by thyroid hormones, suggesting that they recognize the hormonogenic sites on the Tg molecule. The mAb could be divided into at least seven reactivity patterns based on reciprocal competitive inhibition studies, indicating that mTg contains at least seven antigenic regions. DNA sequence analysis of the mAb showed that a large number of V region gene segments encoded the H and L chains. No evidence for preferential use of any V region family or gene segment was found. Gene segments from the VH 7183, Q52, J558, and VH10 families were used by heavy chains, and the V kappa 1, 4, 8, 9, 19, and 21 families were used by kappa-chains. The results indicate that the antigenic epitopes on mTg elicit a very diverse autoantibody response that is derived from a large number of V region gene segments. Many of these autoantibodies show specific reactivity with mTg indicating they recognize species specific epitopes. The results suggest that clonal deletion of autoreactive Ab to certain self-epitopes may not occur.     

Conservation of the most JH proximal Ig VH gene segment (VHVI) throughout primate evolution.

The human VHVI gene segment, the sole member of the VHVI gene family, is remarkable in that it is the most D-proximal VH gene segment and is apparently nonpolymorphic. Here we report that the VHVI gene segment has been remarkably preserved in primate evolution. We were unable to detect RFLP among several primates, and nucleotide sequences of several VHVI gene segments showed remarkable conservation. No differences were detected in the nucleotide sequences of the VHVI gene segment from three unrelated chimpanzees. These findings suggest that the VHVI gene segment has been strongly selected for during primate evolution, suggesting an important immunologic role.     

Mouse heavy chain variable regions: nucleotide sequence of a germ-line VH gene segment

We have constructed a library of Balb/c mouse embryo DNA in the vector Charon 4A. The library was searched for sequences homologous to the VH region of a cloned cDNA of the UPC10 heavy chain mRNA. In this paper, we describe the structure and the partial nucleotide sequence of one of such clones (VH441). The nucleotide sequence of this germ-line gene indicates that it encodes amino-acids 1-98 of the X44 and J601 galactan-binding VH regions, but that it differs from the UPC10 VH segment by four single base changes. The VH gene appears to contain a 101 bases long intervening sequence within a precursor sequence identical to the precursor sequence of UPC10. The 3' non coding sequence of the V gene contains the two conserved sequences found in embryonic V DNA segments, CACAGTG and ACATGAACC, separated by 23 nucleotides and a sequence CACTGTG separated by 33 nucleotides from the first heptamer.